A turbopump may be used in a rocket engine system to pump a liquid propellant, such as liquid oxidizer. Such a turbopump can include a pump section and a turbine section mounted on a common shaft. The turbine section is driven by expansion of a working fluid, such as a hot gas in the system. The turbine section drives the pump section, which pressurizes the liquid propellant for delivery to a combustor or other downstream component in the engine system.